Engineering360: "Flywheels Proposed to Save Energy on Trains"

I think this is an interesting introductory article, which will draw people into the topic, but I found parts of it somewhat misleading.

“Electric and fuel cell vehicles already implement regenerative braking in order to store the energy produced during braking for startup, so why would trains not be able to do so?”

Regeneration is commonly used on tram and metro systems. In the absence of any energy storage system, braking energy can be transferred along the contact line to a nearby vehicle. Only when this is not possible will the energy be dumped into a braking resistor.

Apart from flywheels, energy can be stored using supercapacitors - either mounted on vehicles or installed lineside.

For all such options the cost of installation and return on investment needs to be compared with the "do nothing" scenario of a certain percentage of regeneration without energy storage (which could be quite high in a system with frequent service)

I wish you well with your research.